U.S. Pat. No. 4,870,714 discloses a portable handheld blower/vacuum apparatus having a housing wherein a blower scroll is formed. An impeller driven by a drive motor is accommodated in the blower scroll. When the drive motor is operating, air is supplied to the blower scroll via an air inlet and is discharged from the blower scroll via an air outlet. An air-conducting connecting tube can be mounted in a connecting stub fixed to the housing in the air inlet as well as in the air outlet. The mounted connecting tube and the housing-fixed connecting stub engage one over the other over a pregiven axial length. A bayonet connection is provided in the overlapping region and includes a guide path and a radial cam provided on the connecting tube. The guide path is configured in the surface of the connecting stub. The connecting tube is axially secured by the bayonet connection.
A blower tube is attached to the connecting stub of the air outlet during blower operation. The air inlet is then covered with an inlet screen. In vacuum operation, a vacuum tube is mounted on the connecting stub of the air inlet while a debris collecting bag is connected to the air outlet for the debris drawn in by suction.
During vacuum operation as well as during blower operation, contact of the free end of the vacuum tube or blower tube with the ground is unavoidable whereby considerable forces become effective at the connecting region because of the long lever. This can lead to an unintended loosening of the bayonet connection and cause the connecting tube to drop off. In this way, operation of the apparatus is negatively affected.
U.S. Pat. No. 5,560,078 discloses a portable handheld blower/vacuum apparatus wherein an oval-shaped blower tube is pushed onto the connecting stub at the air outlet of the blower scroll. A latch mechanism is formed outside of the overlapping region and comprises latch tongues arranged on the blower tube which engage over correspondingly configured latch elements on the connecting tube. Mechanical loading applied to the vacuum tube tip operates directly on the latch connection which therefore has to be configured so that corresponding loads can be applied thereto. Nonetheless, damage because of overload cannot be avoided whereby an inadequate attachment of the blower tube to the connecting stub can occur.